1. Field of the Invention
This invention relates to a mechanical shoe expander and more particularly to a brake cable connecting apparatus for connecting a brake cable with a mechanical operating mechanism mainly comprised of a strut and a brake lever.
2. Description of Conventional Arts
A typical brake cable connecting apparatus comprises a mechanical actuator having a strut, a plate-like brake lever which is retained in the strut and which is pivotally mounted on the strut, and a pivot pin.
The mechanical actuator is positioned between a pair of brake shoes and then the strut and the brake lever as components of the mechanical actuator engage with the corresponding brake shoes. When the brake cable connected with the brake lever is operated in a cable operating direction, the brake lever rotates about a pivotally supported point with the strut. Therefore the engaging part of the strut against one brake shoe and the engaging part of the brake lever against the other brake shoe move apart from each other.
In a conventional brake cable connecting apparatus the engaging parts of the brake lever and the strut are urged to approach each other because of a spring force of a shoe return spring. Therefore, the brake lever abuts against a bridge extended between the upper portions of the two facing plates of the strut and a connecting hole of the brake lever, for setting a connecting pin therein, appears at an exterior position of the strut or at a position above an opening of the strut at a cable releasing side. (An example is shown in a paragraph 0015 of the Japanese provisional patent publication number 2001-349360.)
The brake cable is connected with the brake lever; thereafter a holder is clipped on the strut so as to set the brake lever at a certain position in the wider space of the strut.
Instead of the above conventional structure the other type of a holder may be rotatably integrated with the strut. (Refer to FIGS. 5, 6, 7, and 8 of the Japanese provisional patent publication number 2001-349360.)
According to the conventional brake cable connecting apparatus, the engaging parts of the brake lever and the strut against the corresponding brake shoes move to approach each other because of the spring force of the shoe return spring, and the brake lever abuts against the bridge of the strut.
In order to establish this mechanism there needs to be sufficient clearance between each side of the anchor and each brake shoe because of manufacturing dimensional tolerances.
This clearance becomes wider when the brake cable is connected with the brake lever and becomes widest during the brake cable operation.
For the purpose of effectuating a braking force, the brake shoes need to rotate so as to fill up the clearance on either side, depending upon the rotational direction of the brake drum. Therefore, a higher impact load is applied to the anchor, thereby giving lower durability and causing an intensive impact noise.
The holder needs to be designed with sufficient size to be clipped on the outside of the strut, which increases material costs. Furthermore, in order to prevent the holder from detaching from the strut, both the holder and the strut require additional, custom fitting features, which also increases the manufacturing costs thereof.
The conventional separate holder is inconvenient for handling and has the possibility of getting lost.
If the conventional holder is integrated with the strut a rotational axis needs to be employed therebetween, which further increases the costs.
The holder needs to be pushed and clipped on the strut to attach to the strut when the brake cable is connected with the brake lever. The holder needs to rotate in order to establish the attachment to the strut after the brake cable is connected with the brake lever. Therefore, the conventional structure requires more work process.
In addition, employing the separate holder creates the possibility that an attaching work of the holder is accidentally omitted. Employing the integrated holder creates the possibility of failing to rotate the same and further creates the possibility of being attached in an inappropriate position if misassembled.
This invention is made to improve the above-points and to provide a brake cable connecting apparatus with a simple structure offering a simple and accurate ability to assemble.
In order to achieve the above-objectives, this invention presents a brake cable connecting apparatus of a brake actuating mechanism for a drum brake, the brake actuating mechanism comprises: a strut engaging with one brake shoe and a brake lever positioned in a space formed between two facing surface walls of the strut and engaging with the other brake shoe; a proximal end of the brake lever is pivotally supported between the two facing surface walls of the strut while a brake cable is connected to a free end of the brake lever by a connecting pin and the brake actuating mechanism moves the brake shoes away from each other as a result of relative rotation of the strut and brake lever about a pivotally supporting point therebetween by operation of the brake cable, wherein a resilient member is provided on a rotating trajection of the brake lever relative to the strut; when the brake lever, at an external position out of the space of the strut where the connecting pin can link the brake cable and the brake lever, rotates and moves in a cable operating direction, either the brake lever or the strut deforms the resilient member to allow the free end of the brake lever to pass into the internal position in the space of the strut thereby securing the linkage of the connecting pin, the brake lever, and the strut, and thus preventing removal of the connecting pin; and when the brake lever at the internal position rotates and moves in a cable releasing direction, either the brake lever or the strut abuts against the resilient member thereby inhibiting the brake lever from rotating in the cable releasing direction.
The brake cable connecting apparatus described above can provide a simple connection between the free end of the brake lever and the brake cable by the connecting pin.
By simply positioning the resilient member on the rotating trajection of the brake lever this allows the brake lever to be at a position enabling the connecting pin to link the brake cable and the free end of the brake lever.
Further, after the brake cable is connected to the free end of the brake lever by the connecting pin, the resilient member, as a result of only operating the brake cable, can prevent disengagement of the brake cable from the brake lever. This structure can also eliminate the possibility of omitting a manual attaching work of the holder.
Furthermore, there is no need to add processes to make particular features either on the brake lever or the strut for mounting the resilient member. The brake cable connecting apparatus as described above may have the resilient member installed in the strut.
This disclosure facilitates the mounting work of the resilient member on the strut. The brake cable connecting apparatus as described above may have the resilient member installed in the brake lever.
This disclosure facilitates the mounting work of the resilient member on the brake lever. The brake cable connecting apparatus as disclosed above may be such that an operating portion that makes the resilient member deform is formed on the resilient member, when the operating portion is operated while rotating the brake lever in the cable releasing direction from the interior position to the exterior position, an abutment of the brake lever or the strut against the resilient member is released, thereby permitting a passage of the free end of the brake lever.
This disclosure facilitates disengaging the brake cable from the brake lever. The resilient member can be deformed as a result of only operating the operating portion. Therefore, the brake cable can be taken away from the brake lever.